Differential mechanism



April 7, 1925.

I. C. WOODWARD DIFFERENTIAL MECHANISM Patented Apr, 7, 1925.,

nine

IRVING C. WOODWARID, OF SYRACUSE, NEW YORK.

DIFFERENTIAL MECHANISM.

Application filed, October 27, 1923. Serial No. 671,132.

To all whom it may concern:

Be it known that I, IRvINe C. Woonwnnn, a citizen of the United States of America, and a resident of Syracuse, in the county of Onondaga and State of New York, have invented a new and useful Improvement in Differential Mechanisms, of which the following is a specification. i

The main objects of this invention are to provide an improved form of differential mechanism for motor vehicles wherein a pair of driven members are positively driven as a unit under normal conditions, but have a differential action under some circumstances; and to provide a vehicle differential mechanism of the above kind wherein difierential rotation is prevented until the effort of the driven members to differentiate in speed reaches a predetermined amount.

An illustrative embodiment of this in-- vention is shown in the accompanying drawings, wherein Figure 1 is a section taken through the center of a differential mechanism constructed in accordance with this invention.

Fig. 2 is a section taken on the line 22 of Figure 1.

Fig. 3 is a section taken on the line 3-3 of Figure 1.

While it is appreciated that the standard form of planetary gear differentials operates in a most perfect manner under certain con- 7 ditions, one of the purposes in making the present differential mechanism is to avoid the dangers incident to the standard form of differential gearing when the road conditions are not good, or when one wheel bounces from the road and speeds up as is possible with the planetary gear differential mechanism. Such speeding sometimes results in skidding, and if not, in at least a needless wearing of the tires and consumption of fuel, since when one wheel is spinning the power is dissipated in spinning the wheel instead of driving the wheel having good traction. By means of the present construction the advantages of a single axle drive mechanism wherein there is no differential mechanism are more or less attained without including the objectionable feature of the single axle wherein upon making a turn of short radius there is a. tendency to overload and stop theengine due to its effort in dragging the outside wheel over the road to the extent necessary 1n making the turn.

The present construction is a compromise between the single or solid axle type of drive and the two-axle and differential gearing construction commonly employed, in that while it will permit differential rotation between the driven wheels when the effort to differentiate reaches a predetermined value, the two wheels will generally be driven at the same rate, regardless of whether one wheel bounces from the road or meets with a more slippery surface than that engaged by the other wheel.

it is a further aim of the invention to provide a much simpler construction than that generally employed to allow for differ ential motion between the driven axles, and thus to avoid the liability of such mechanism becoming injured under excessive strains.

The drawing shows the differential mechanism as embodying a .couplingconstructed in accordance with the invention set forth in my copending application, Serial No. 663,988, filed September 21, 1923, for an improvement in clutches.

In the form shown, the vehicle drive mechanism to which this invention is applied comprises the usual frame structure or housing 1, power shaft 2, and coaxial driven shafts 3 and 4c journaled in roller bearings 5 of the housing 1. Arranged be-' tween the driven shafts 3 and 4, is a coupling 6 constructed in accordance with the invention set forth in my-a-bove mentioned copending application, and involving the use of a pair of telescoping parts of normally different cross-sectional shapes, one of which is resilient and distorted by its assembly with the other part, and both of which parts are respectively connected to the driven shafts 3 and 4, whereby the relative rotation ofsaid shafts is resisted by the resilience of the distorted part.

In the specific embodiment herein shown, the coupling 6 includes coaxial loosely interfitting rigid parts 7 and 8, splined as shown at 9 and 10 respectively to the shafts 3 and 4, and coacting with a resilient sleeve 11, which is arranged to resist relative rotation of said rigid parts, whereby said driven shafts are yieldingly clutched together so as to be capable of differential action only when the coupling is subjected to its maximum load.

The parts"? and 8-include hub parts 12 and 13 1?espectively supported in thebear-m ings 5, and loosely interiittinghub parts lit and 15 respectively arranged to axially'aline the driven shafts 8 and 4c, which-extend through the splined openings 9 and 10 respectively of the parts '?-and 8.: a

Rigidly secured to the part 7, as by bolts 16, or otherr suitahle {fastening a means, is. a ringgearmli, whichaineshesl.with axpinion 18 fixed on the power shaft 2, whereby the; part-Z and vshajitfi are positiyely drivenaat all times; .7

The hub, 114x015 the right-part7 provides bearing far/e419 oi: nonecircularicrossesection'- sleeve-11 1s telescop i on which-the, resilienticall arrangede'g The sleeve; 11 is of :normall to litareundthe hub part ll. 7 The diameter of the; .i'nnersurtace, ot the resilient sleeve 11 isslightlvgreaterthan theawerage diameter {of the hubpart. 1. space 20 for oil between, the telescoping parted:

Formed 1 on the outer i end of the resilient sleeve: llis plurality 110i?- projections or lugs 21, which-formclutch. teeth for engage the member 8,.wherelay-saidsleeweaand nieinher 8 are DOSltlVGl Y clutched to ether so: as O to rotate; a unit. ,The. relativcarrangernentgvot-theglugsand slots 22 permits a limited during anyrc-la wve;rotatienofthe resilient element 11 anduthe rigid pant-7,--due; to,t he non-circidar:shape-of thebe IliflgiflCG 19.

In o.peration,-the .shal pposi vely driven at all ztiines a through the ring gear 17 and.rigidxniemben,7,totwnich it is splined- Up, to the niaxlniuni hold ng ,ypowernof; the;

clutchfi, theshafts are drivenas a unit.::, If the circumstances --are 'suchi that the strain; on the clutchis sufficient to overcornez-vthe holdingipeiv er the clutch}, the resilient; eieme part 1 1- 7 thereby we u tial ritGtlQllybftWQl A and 14;- When, ho vever the veh cle is A ver r1116.-

straight-rpathore-r 4a:slipperyeor rouglnroad, or on a1steep; grade,;thecsha:tts3. and; lrotate as a unit and prevent-;skidding, :racing'ioi' thev enginegsloss of traction,-:and. other trou-' oles inherent in the usual di,erentialrgear 1ng.;;.:

dVith respect :to. the operation of this deerv vice as compared; with ,the planetary :diflie entia-l now; commonly einployed'ln the-driv ing mechanisms-rim auto:\nobiles,-.,;:applicantsi constnuction apro-vides. 15- 11101: fixed resistancer.-to drtlerentialemotion. sunder..1a1l fiOl'lCll'll-lofiilpf roperatioirlgof the .jvehicle :circu-lar cross-section, aand is; distorted-a thus 1 providing a adialgrnolve'rnentmoi the sleeref ll 1 mm to-the ra n1be1 8,,-.which s necessary 11 will :slipnon the hub- 1 gzqsonien clifieren-e lVith the planetary arrangement there is a one to two gear ratio between the housing of the diit'erential; which carries the ring gear, and the driven axle when the remaining axle is held from moving, as would be the case whenone wheel has good traction and the other none at all or insufficient traction to prevent it from spinning. Such condition is extremely dangerous and may result in throwing -aearfrom the road when the driven wheels alternately have good and .e-niavghavei considerable inoinentun'nas there his their-much. unavoidable effort s ,eed i:

changing even though: the. motor is running 8. at a fined: rate;v 1 In applicants construction' :ncither'ot' the; driven iaxlescan exceed the 'speeds otthe ring gearundenany ordinary aicondition. The niaXiinunr-speed which-otheengine is ableto impart; to thC-GILVGDWHXIQS' -;is thexsaine as the speed of the ring geaixa, In making a turn differential motion ;be,

.;tweenthe two axles is dependent upon the,

aditi'erenceiiu resistanceto rotation 0f the driven wheels equaling. certain predeter 1nined percentage of the. power delivered to y the 11iOEOl,;-,plllS tllQ lllOlnfcilttllll Of' the car.

;-.;Thus, applicants dilterential-inechanisnris designcdto oflcrza; resistance to differentialctionwvhich proportional-.- to the average x9 speed, load, and power delivered byithe mofidlOl. This diLtleren-t-i l mcchanis n does not have the needless ircedonr of movement-that v the planetary gear form has, and,-th crefore,

no "differential action -takes .-;pl ace except W DlOStJ-Q ed is, when a carhas .conside I V H a i hen-amahing .-;turn. planetary-gear; erent ahofieis least resistance to diiierential lnoticn just; 1

when such 1 motion. is worsethanaiseless. when the power, speed and load are lightes and, the inaizinaun' resistance to i difierenitia, inoct/ 1011lllPQn-al luinCleQSe, innpoweri and speed.

A further undesirabl additionlto theresistance 1 a planetarycgear 5 clilfer'entiali-,is

-, ideveloped by the-..thrust or tooth-pressure lie-- ,ithe .car in rapidl ";Inaltingmturn.

" ry-geai transmission, therefore, re

needless loss of;powe r,--bot-h to too 11 iniuch l EEEClDITbOLE,'SLCtlOH under. son". :13 um stances, and; :a,: bindin aactionibetween-the gearsaxundernother' circumstances where .a- 'aditterential: motion: is i vactually :requiredw A though-glint one specific:embodiment of fetl ii ention ihasbeenihercin-shown and mdescrrbedgdt. will be understood that @IlUDlerous-details .of the censtruction ShGWnlDLlYn be. alteneda or omitted .without' departing-1 from-the spirit-of this invention as definedififi 1 by the iiollowing, Qltllll'lSzm l. A vehicle ,dIlYG1H1CCl1tlIllSD1 comprising a pain-lot coaxial s-SlltakltS, means/for positivelyadriv-in-g one 0% said shafts, a coupling between said shafts comprising a member of non-circular form secured to one of the shafts and a coacting member mounted for rotation with the remaining shaft and including a resilient element adapted to resiliently conform to the surface of said coacting non-circular member.

2. A differential mechanism including a drivin member, a pair of driven members connected thereto, and a coupling connecting together said driven members, said coupling having telescoping parts of normally different .ross sectional shapes, one of said parts being of noncircular cross section, the oti er of said parts being resilient and distorted to conform to said non-circular part whereby said driven members are normally secured against rolatire rotation by the resilience of said distorted part.

3. A differential mechanism including a driving member, a pair of coaxial driven shafts connected thereto, and a coupling spiined on said driven shafts, said coupling having telescoping parts of normally different cross-sectional shapes, one of said parts being of non-circular cross-section, the

other of said parts being resilient and distorted to conform to said non-circular part whereby said driven shafts are normally secured against relative rotation by the resilience of said distorted part.

4:. A differential mechanism including a driving member, a pair of coaxial driven shafts connected thereto, a coupling yieldingly connecting together said driven shafts, said coupling including a pair of interfitting parts splined respectively to the inner ends of said. shafts and adapted for relative r0- tation during any differential action of said shafts, and a resilient element telescopically arranged with respect to one of said parts and having interlocking engagement with the other part, said element and one part being normally of different cross sectional shapes and said resilient element being distorted to conform to said one part whereby said driven shafts are yieldingly secured against relative rotation by the resilience of said distorted member.

Signed at Syracuse this 24th day of Oct,

IRVING o. WOODWARD. 

